Method and Apparatus for Intra Coding for a Block in a Coding System

ABSTRACT

A method and apparatus of Intra coding for a block in a coding system. The method includes receiving input data associated with a current block; determining a current Intra prediction mode for the current block; deriving prediction samples for the current block based on reconstructed neighboring samples according to the current Intra prediction mode, wherein a predicting value representing a single prediction value for the current block is determined based on at least two corner samples corresponding to the current block according to the current Intra prediction mode; and applying encoding or decoding to the input data associated with the current block using the prediction samples derived for the current block.

CROSS REFERENCE TO RELATED APPLICATIONS

The present invention is a Continuation of pending U.S. patentapplication No. 14/480,788, filed on Sep. 9, 2014, which claims priorityto U.S. Provisional Patent Application, Ser. No. 61/892,240, filed onOct. 17, 2013, entitled “Methods of Intra Coding Improvement”. Thepriority applications are hereby incorporated by reference in theirentireties.

FIELD OF THE INVENTION

The present invention relates to video coding. In particular, thepresent invention relates to Intra coding.

BACKGROUND AND RELATED ART

Three-dimensional (3D) television has been a technology trend in recentyears that is targeted to bring viewers sensational viewing experience.Multi-view video is a technique to capture and render 3D video. Themulti-view video is typically created by capturing a scene usingmultiple cameras simultaneously, where the multiple cameras are properlylocated so that each camera captures the scene from one viewpoint. Themulti-view video with a large number of video sequences associated withthe views represents a massive amount data. Accordingly, the multi-viewvideo will require a large storage space to store and/or a highbandwidth to transmit. Therefore, multi-view video coding techniqueshave been developed in the field to reduce the required storage spaceand the transmission bandwidth. In three-dimensional and multi-viewcoding systems, the texture data as well as depth data are coded.

For depth map, the Simplified Depth Coding (SDC), which is also termedas Segment-wise DC Coding, is an alternative Intra coding mode. WhetherSDC is used is signalled by a SDC flag at coding unit (CU) level. ForSDC, the depth block is Intra predicted by a conventional Intra mode ordepth modelling mode 1. The partition size of SDC-coded CU is always2N×2N and therefore there is no need for signaling in the bitstreamregarding the block size of SDC-coded CU. Furthermore, instead of codedas quantized transform coefficients, the SDC-coded residuals arerepresented by one or two constant residual values depending on whetherthe depth block is divided into one or two segments.

According to existing three-dimensional video coding based on HEVC(3D-HEVC), certain information is signalled for SDC-coded blocks. Theinformation signalled includes:

1. type of segmentation/prediction of the current block. Possible valuesare

-   -   i. DMM (Depth Modelling Mode) Mode 1—Explicit Wedgelets (2        segments)    -   ii. Planar (1 segment)

2. For the DMM, additional prediction information (e.g., partitioninformation) is coded.

3. For each resulting segment, a residual value (in the pixel domain) issignalled in the bitstream

In the depth coding process, the depth samples are first mapped tolimited depth values. The limited depth values are represented by aDepth Lookup Table (DLT), and after mapping depth samples into limiteddepth values, these limited depth values are used as the indexespointing to entries of the DLT. Consequently, residuals can be generatedby taking the difference between the DLT index of the predictor and theoriginal depth samples; the index residual can then be coded and sent tothe decoder. The depth values present in a depth map are usually limitedto a number smaller than the total number that can be represented by adepth capture device. Therefore, the use of DLT can reduces the bitdepth required for residual magnitudes. This mapping table istransmitted to the decoder so that the inverse lookup from an index to avalid depth value can be performed at the decoder.

At the encoder side, the residual index i_(resi) to be coded into thebitstream, is determined according to:

i _(resi) =I(d _(orig))−I(d _(pred)),  (1)

where d_(orig) denotes an original depth value determined for the depthblock (e.g., the mean value of the original depth block), d_(pred)denotes the predicting depth value (e.g., the mean value of theprediction samples for the depth block), and I(.) denotes the IndexLookup Table. The computed residual index i_(resi) is then coded with asignificance flag, a sign flag and with ┌log₂ d_(valid)┐ bits for themagnitude of the residual index, where d_(valid) denotes the number ofvalid depth values and ┌x┐ is a ceiling function corresponding to thesmallest integer not less than x.

The Depth Lookup Table takes advantage of the sparse property of thedepth map, where only a small number of depth values out of a fullavailable depth range (e.g., 2⁸) will typically be present in the depthmap. In the encoder, a dynamic depth lookup-table is constructed byanalyzing a number of frames (e.g. one Intra period) of the inputsequence. This depth lookup-table is used during the coding process toreduce the effective signal bit-depth of the residual signal.

In order to reconstruct the lookup table, the encoder reads apre-defined number of frames from the input video sequence to be codedand scans all samples for presence of the depth values. During thisprocess a mapping table is generated that maps depth values to existingdepth values based on the original uncompressed depth map.

The Depth Lookup Table D(.), the index Lookup Table I(.), the DepthMapping Table M(.) and the number of valid depth values d_(valid) arederived by the following process that analyses the depth map D_(t):

-   -   1. Initialization        -   boolean vector B(d)=FALSE for all depth values d,        -   index counter i=0.    -   2. Process each pixel position p in D_(t) for multiple time        instances t:        -   Set B(D_(t)(p))=TRUE to mark valid depth values.    -   3. Count the number of TRUE values in B(d). The result is set to        the value for d_(valid).    -   4. For each d with B(d)==TRUE:        -   Set D(i)=d,        -   Set M(d)=d,        -   Set I(d)=i, and        -   i=i+1.    -   5. For each d with B(d)==FALSE:        -   Find {circumflex over (d)}=arg min|d−{circumflex over (d)}|            and B({circumflex over (d)})==TRUE        -   Set M(d)={circumflex over (d)}.    -   6. Set I(d)=I({circumflex over (d)}) .

As mentioned above, there are two types of segmentation and predictionin the existing SDC. The respective processes for the two types ofsegmentation and prediction are described as follows.

-   -   DMM mode:        -   Edge information is defined by start/end side and            corresponding index.        -   The DC prediction value (i.e., predicting depth value            (d_(pred))) for each segment are predicted by neighboring            depth values (also referred as neighboring depth samples or            neighboring samples in this disclosure) as shown in FIG. 1.            Two examples of depth blocks (110 and 120) are shown in FIG.            1, where each depth block is divided into two segments as            shown by the dashed line. The reconstructed neighboring            depth samples used to generate prediction samples for block            110 are indicated by reference numbers 112 and 114, and the            reconstructed neighboring depth samples used to generate            prediction samples for block 120 are indicated by reference            numbers 122 and 124 in FIG. 1.    -   Planar mode:        -   Generate the predictors (i.e., prediction samples) of the            Planar mode as shown in FIG. 2. Linear interpolation is used            to generate predictors for the right column and the bottom            row as shown in FIG. 2A. For the right column, the linear            interpolation is based on depth values at A and Z. For the            bottom row, the linear interpolation is based on depth            values at B and Z. After the right column and the bottom row            are interpolated, the predictors for the rest of depth            positions are bilinear interpolated using four respective            depth samples from four sides as shown in FIG. 2B.        -   The DC prediction value (i.e., a single predicting depth            value (d_(pred)) for the block) is the mean of the            predictors of the Planar mode.

In the above derivation processes, prediction sample refers to thepredicted value generated by the Intra coding mode, which may be DMMMode 1 or the Planar mode in the existing 3D-HEVC. The reconstructionprocess for the Planar mode at the decoder side is illustrated in FIG.3. The DC prediction value (Pred_(DC)) for the current depth block (310)is determined based on the mean of the predicted depth samples for thecurrent depth block. The predicted depth values for the current depthblock are derived using linear interpolation (right column and bottomrow) and bilinear interpolation (other depth samples) of neighboringreconstructed depth values. In FIG. 3, the predicted depth values areshown in the current depth block (310). To reconstruct the depth value(Rec_(DC)) for the current depth block, a DLT index is first obtained byadding residual index to the DLT index of Pred_(DC). The reconstructeddepth value (Rec_(DC)) for the current depth block is then obtained byapplying inverse lookup on this derived index. The residual pixel value(pixel domain) is then obtained by taking difference of Rec_(DC) andPred_(DC). The final reconstructed depth block (320) is derived byadding this residual pixel value to each prediction sample of thecurrent block.

The reconstruction process for the DMM Mode 1 at the decoder side isillustrated in FIG. 4. The current depth block (410) is divided into twosegments. The DC prediction values (Pred_(DC1) and Pred_(DC2)) for thetwo segments of the current depth block (410) are determined based onrespective neighboring reconstructed depth values. In FIG. 4, thepredicted depth values are shown in the current depth block (410). Toreconstructed depth values (Rec_(DC1)and Rec_(DC2)) for the two segmentsof the current depth block, two DLT indexes are first obtained by addingcorresponding residual index to the DLT index of Pred_(DC1) andPred_(DC2). The reconstructed depth value (Rec_(DC1) and Rec_(DC)2) forthe current depth block is then obtained by applying inverse lookup onthis derived index. The residual pixel value (pixel domain) is thenobtained by taking difference of Rec_(DC1) and Pred_(DC1), and Rec_(DC2)and Pred_(DC2), respectively. The final reconstructed depth block (420)is derived by adding this residual pixel value to each prediction sampleof each segment of the current block.

In the conventional SDC for depth block coding, only limited predictionmodes are provided. It is desirable to extend the prediction modes toimprove coding efficiency.

BRIEF SUMMARY OF THE INVENTION

A method and apparatus for a block in a coding system are disclosed. Incertain embodiments, a method of Intra coding for a block in a codingsystem comprises: receiving input data associated with a current block;determining a current Intra prediction mode for the current block;deriving prediction samples for the current block based on reconstructedneighboring samples according to the current Intra prediction mode,wherein a predicting value representing a single prediction value forthe current block is determined based on at least two corner samplescorresponding to the current block according to the current Intraprediction mode; and applying encoding or decoding to the input dataassociated with the current block using the prediction samples derivedfor the current block.

In other embodiments, an apparatus for Intra coding of a block in acoding system comprises one or more electronic circuits configured to:receive input data associated with a current block; determine a currentIntra prediction mode for the current block; derive prediction samplesfor the current block based on reconstructed neighboring samplesaccording to the current Intra prediction mode, wherein a predictingvalue representing a single prediction value for the current block isdetermined based on at least two corner samples corresponding to thecurrent block according to the current Intra prediction mode; and applyencoding or decoding to the input data associated with the current blockusing the prediction samples derived for the current block.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates two examples of Depth Modelling Mode (DMM) for depthcoding based on Simplified Depth Coding (SDC), where the depth block isdivided into two segments and each segment is modelled as a uniformarea.

FIG. 2A and FIG. 2B illustrate the linear interpolation and bilinearinterpolation used to generate prediction samples for the depth blockbased on reconstructed neighboring depth samples according to the Planarmode in SDC.

FIG. 3 illustrates an exemplary reconstruction process for SimplifiedDepth Coding (SDC) using the Planar mode.

FIG. 4 illustrates an exemplary reconstruction process for SimplifiedDepth Coding (SDC) using the Depth Modelling Mode (DMM) Mode 1.

FIG. 5 illustrates an example of sample-based Simplified Depth Coding(SDC) for Horizontal mode.

FIG. 6 illustrates an example of sample-based Simplified Depth Coding(SDC) for the Vertical mode.

FIG. 7 illustrates an exemplary reconstruction process in the decoderside for sample-based Simplified Depth Coding (SDC) using the Horizontalmode according to an embodiment of the present invention.

FIG. 8 illustrates an exemplary reconstruction process in the decoderside for sample-based Simplified Depth Coding (SDC) using the Verticalmode according to an embodiment of the present invention.

FIG. 9 illustrates an example of using different subsets of predictionsamples for calculating predicting depth value in the Horizontal Intramodes for SDC.

FIG. 10 illustrates an example of using different subsets of predictionsamples for calculating predicting depth values in the Vertical Intramodes for SDC.

FIG. 11 illustrates an example of using all samples, a single sample,partial samples, or two corner samples of a reconstructed neighboringdepth column to calculate predicting depth values in the HorizontalIntra mode.

FIG. 12 illustrates an example of using all samples, a single sample,partial samples, or two corner samples of a reconstructed neighboringdepth row to calculate predicting depth values in the Vertical Intramode.

FIG. 13 illustrates an exemplary flowchart of Simplified Depth Coding(SDC) for depth data using extended Intra prediction mode set accordingto an embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

In order to improve the coding efficiency of SDC coding, embodimentsaccording to the present invention uses extended prediction modes forSDC coding, where the extended prediction modes includes HorizontalIntra mode, Vertical Intra mode or both in additional to theconventional Planar mode and DMM Mode 1. The Intra prediction mode forSDC is also referred as Intra prediction type in this disclosure. TheHorizontal Intra mode and the Vertical Intra mode are also referred asHorizontal mode and Vertical mode in this disclosure. For example, theset of extended Intra prediction types, of segmentation/prediction forthe current block may correspond to:

a. DMM Mode 1—Explicit Wedgelets (2 segments)

b. Planar (1 segment)

c. Horizontal (1 segment)

d. Vertical (1 segment)

For the DMM mode, additional prediction information is coded to indicatethe partition. For each resulting segment, a residual value (in thepixel domain) is signalled in the bitstream. The two additional types ormodes, i.e., Horizontal and Vertical Intra prediction process isdescribed as follows

-   -   Horizontal Mode:        -   Generate the predictors of the Horizontal Intra mode as            shown in FIG. 5, where the reconstructed neighboring depth            column (510) adjacent to the current left block boundary of            the current block (520) is used to generate the prediction            samples. Each sample in the neighboring column is used to            generate the prediction samples for a corresponding row of            the current block.        -   The DC prediction value (i.e., a single predicting depth            value (d_(pred)) for the block) is the mean of the            predictors or the mean of the subset of the predictors of            the Horizontal mode as shown in FIG. 5.    -   Vertical Mode:        -   Generate the predictors of the Vertical Intra mode as shown            in FIG. 6, where the reconstructed neighboring depth row            (610) adjacent to the current top block boundary of the            current block (620) is used to generate the prediction            samples. Each sample in the neighboring row is used to            generate the prediction samples for a corresponding column            of the current block.        -   The DC prediction value (i.e., a single predicting depth            value (d_(pred)) for the block) is the mean of the            predictors or the mean of the subset of the predictors of            the Vertical mode as shown in FIG. 6.

An example of the reconstruction process for the Horizontal mode and theVertical mode at the decoder side is illustrated in FIG. 7 and FIG. 8respectively. In FIG. 7, block 710 corresponds to the predicted depthvalues and block 720 corresponds to the reconstructed block using theHorizontal mode. The DC prediction value (i.e., predicting depth value),Pred_(DC) is derived for the current block 710. The Pred_(DC) is addedto the residual received to form the reconstructed residual value forthe block, Rec_(DC). This reconstructed residual value is then updatedby the individual prediction samples derived according to Horizontalmode to form reconstructed depth samples for the block 720. In FIG. 8,block 810 corresponds to the predicted depth values and block 820corresponds to the reconstructed block using the Vertical mode. Theprocess to reconstruct DC prediction value for the block, Rec_(DC) issimilar to the case for the Horizontal mode. The reconstructed depthvalue for the block 820 is derived from

d _(rec) =I ⁻¹(i _(resi) +I(d _(pred))),  (2)

with I⁻¹(.) denoting the inverse Index Lookup table. At the decoderside, the reconstructed residual R, is derived by

R _(rec) =d _(rec) −d _(pred).  (3)

Each prediction sample of the current block or prediction unit (PU) isthen updated with the reconstructed residual, i.e., the reconstructedresidual is added to each prediction sample as the new predictionsample. Accordingly, the prediction samples of Horizontal/Vertical modewill be the prediction samples of the Horizontal/Vertical mode plus anoffset value, where the offset value is derived from the residual index.

In another example, all the prediction samples of the current block orPU will be replaced by a same reconstructed depth value derived from

d _(rec) =I ⁻¹(i _(resi) +I(d _(pred))),

with I⁻¹(.) denoting the inverse Index Lookup table.

In the above example, the set of extended Intra prediction types ofsegmentation/prediction corresponds to {DMM Mode 1, Planar mode,Horizontal mode, Vertical mode}. However, other sets of extended Intraprediction types may also be used to practice the present invention. Forexample, the set of extended Intra prediction types may correspond to:

-   -   {DC mode, DMM Mode 1, Horizontal mode, Vertical mode}    -   {Planar mode, DMM Mode 1, Horizontal mode, Vertical mode}    -   {Planar mode, DC Mode, Horizontal mode, Vertical mode}    -   {DMM mode 1, Planar mode, Horizontal mode, Vertical mode,        Diagonal Mode 2, Diagonal Mode 8}        where Diagonal Mode 2 and Diagonal Mode 8 are the Intra        prediction modes for texture video data as described in the HEVC        standard (H.265: High efficiency video coding, Recommendation        ITU-T H.265. April 2013).

The order of the type for generating prediction samples may also bechanged. Based on this order, a truncated unary code can be used tosignal the type selected for the current block. An example of themodified coding table with these two additional modes, i.e., Horizontaland Vertical modes are shown in Table 1.

TABLE 1 depthIntraModeSet 0 1 2 3 depthIntraModeMaxLen 1 3 3 2DepthIntraMode Associated name depth_intra_mode 0 INTRA_DEP_SDC_PLANAR 0— 0 — 1 INTRA_DEP_NONE 1 0 — 0 2 INTRA_DEP_SDC_DMM_WFULL — — — 1 3INTRA_DEP_DMM_WFULL — 1 3 — 4 INTRA_DEP_DMM_CPREDTEX — — — 2 5INTRA_DEP_DMM_WPREDTEX — 2 2 — 6 INTRA_DEP_CHAIN — 3 1 — 7INTRA_DEP_SDC_HOR 2 3 8 INTRA_DEP_SDC_VER 3 4

An example of the binarization for depth Intra mode with additionalHorizontal and

Vertical modes is shown in Table 2.

TABLE 2 Bin String (cLog2CbSize == 3 && PartMode[xC][yC] == PART_2N ×2N) || cLog2CbSize == (cLog2CbSize >3 && cLog2CbSize <6) 3 && PartModecLog2Cb Name of depth_intra_mode !depth_intra_mode_offset_flagdepth_intra_mode_offset_flag [xC][yC] == PART_N × N Size == 6INTRA_DEP_SDC_PLANAR 0 — 0 INTRA_DEP_CHAIN 10 111 —INTRA_DEP_DMM_WPREDTEX 110 110 — INTRA_DEP_DMM_WFULL 111 10INTRA_DEP_NONE 0 0 10 INTRA_DEP_SDC_DMM_WFULL 10 — —INTRA_DEP_DMM_CPREDIEX 110 — — INTRA_DEP_SDC_HORIZONTAL 1110 110INTRA_DEP_SDC_VERTICAL 1111 111

For the set of extended Intra prediction types for SDC coding accordingto embodiments of the present invention, the predicting depth value (d_(pred)) in those Intra prediction modes can be calculated from allprediction samples, or the prediction samples after sub-sampling, or asubset of the prediction samples. Since the prediction samples arederived based on reconstructed neighboring depth samples, the predictingdepth value (d _(pred)) may also be derived directly using thereconstructed neighboring depth samples of the current coding block. Thefunction used to derive the predicting depth value can be the mean,median, maximum, minimum, or a linear combination of the predictionsamples, the prediction samples after sub-sampling, the subset of theprediction samples, or the neighboring reconstructed samples of thecurrent coding block.

When a subset of the prediction samples is used to derive the predictingdepth value (d_(pred)) for the Intra prediction modes, any of thefollowing subsets can be used:

The first row and first column of current coding block,

The center prediction sample of current coding block,

The four corner samples of current coding block,

The two corner samples of the first/last/one row of current codingblock, and

The two corner samples of the left-most/right-most/one column of currentcoding block.

In another example, different subsets of the prediction samples can beused for difference Intra prediction modes for SDC. For example, for theHorizontal Intra mode, the two corner samples (shown as two black dots)of the left-most column can be used to calculate the predicting depthvalue as shown in FIG. 9. Alternatively, any other column such as theright-most column may also be used for Horizontal Intra mode to derivethe predicting depth value (d_(pred)). As for the Vertical Intra mode,the two corner samples (shown as two black dots) of the first row can beused to calculate the predicting depth value as shown in FIG. 10.Alternatively, any other row such as the last row can also be used todetermine for the Vertical Intra mode to derive the predicting depthvalue (d_(pred)).

In another embodiment of the present invention, the neighboringreconstructed samples are used to derive the predicting depth value. Forexample, for the Horizontal Intra mode, all samples, a single sample,partial samples, or two corner samples of the reconstructed neighboringdepth column (1110) adjacent to the left block boundary of the currentblock 1120 can be used to calculate the predicting depth value as shownin FIG. 11. As for the Vertical Intra mode, all samples, a singlesample, partial samples, or two corner samples of the reconstructedneighboring depth row (1210) adjacent to the top block boundary of thecurrent block (1220) can be used to derive the predicting depth value asshown in FIG. 12.

The performance of a 3D video coding system incorporating an extendedIntra prediction mode set according to an embodiment of the presentinvention is compared to that of a conventional system based on HTM-8.0(High Efficiency Video Coding based 3D Coding Test Model, version 8.0).The types of Intra prediction for the HTM-8.0 include DMM Mode 1 andPlanar mode. The embodiment according to the present invention furtherincludes Horizontal mode and Vertical mode. The performance comparisonis based on different sets of test data listed in the first column. Thetest results of the system incorporating an embodiment of the presentinvention under the common test conditions (CTC) and under the all-Intra(AI) test conditions are shown in Table 3 and Table 4, respectively. Asshown in the tables, the system with extended Intra prediction mode setaccording to the present invention can achieve over 0.1% BD-rate savingin some cases. The average decoding time can be reduced by more than 3%.

TABLE 3 Video Video Synth PSNR/ PSNR/ PSNR/ video total total Enc DecRen Video 0 Video 1 Video 2 bitrate bitrate bitrate time time timeBalloons 0.00% −0.16% −0.04% −0.06% −0.09% −0.05% 101.4% 98.8% 99.8%Kendo 0.00% 0.14% −0.18% 0.00% −0.08% −0.10% 100.1% 96.7% 100.2%Newspapercc 0.00% 0.04% 0.05% 0.01% −0.04% 0.04% 100.7% 93.9% 98.9%GhostTownFly 0.00% 0.16% −0.03% 0.02% −0.15% −0.19% 101.6% 93.3% 98.6%PoznanHall2 0.00% 0.22% −0.19% 0.00% −0.03% −0.16% 99.5% 97.9% 100.4%PoznanStreet 0.00% 0.15% 0.13% 0.05% −0.02% −0.10% 100.4% 98.2% 100.5%UndoDancer 0.00% −0.02% −0.26% −0.04% −0.07% −0.20% 100.4% 95.8% 96.1%1024 × 768 0.00% 0.01% −0.06% −0.02% −0.07% −0.04% 100.8% 96.5% 99.6%1920 × 1088 0.00% 0.13% −0.09% 0.01% −0.07% −0.16% 100.5% 96.3% 98.9%average 0.00% 0.07% −0.08% 0.00% −0.07% −0.11% 100.6% 96.4% 99.2%

TABLE 4 Video Video Synth PSNR/ PSNR/ PSNR/ video total total Enc DecRen Video 0 Video 1 Video 2 bitrate bitrate bitrate time time timeBalloons 0.00% 0.00% 0.00% 0.00% −0.01% −0.04% 100.3% 94.4% 99.4% Kendo0.00% 0.00% 0.00% 0.00% −0.02% −0.02% 100.6% 99.1% 102.9% Newspapercc0.00% 0.00% 0.00% 0.00% −0.02% −0.05% 100.9% 101.2% 102.5% GhostTownFly0.00% 0.00% 0.00% 0.00% −0.35% −0.32% 101.9% 90.4% 101.3% PoznanHall20.00% 0.00% 0.00% 0.00% −0.12% −0.17% 101.8% 97.8% 98.8% PoznanStreet0.00% 0.00% 0.00% 0.00% −0.15% −0.17% 101.7% 99.0% 94.6% UndoDancer0.00% 0.00% 0.00% 0.00% −0.07% −0.10% 101.8% 94.8% 100.6% 1024 × 7680.00% 0.00% 0.00% 0.00% −0.02% −0.04% 100.6% 98.2% 101.6% 1920 × 10880.00% 0.00% 0.00% 0.00% −0.17% −0.19% 101.8% 95.5% 98.8% average 0.00%0.00% 0.00% 0.00% −0.11% −0.13% 101.3% 96.7% 100.0%

FIG. 13 illustrates an exemplary flowchart of Simplified Depth Coding(SDC) for depth data using extended Intra prediction mode set accordingto an embodiment of the present invention. The system receives inputdata associated with a current depth block as shown in step 1310. Forencoding, the input data associated with the depth block corresponds tothe depth samples to be coded. For decoding, the input data associatedwith the current depth block corresponds to the coded depth data to bedecoded. The input data associated with the current depth block may beretrieved from memory (e.g., computer memory, buffer (RAM or DRAM) orother media) or from a processor. A current Intra prediction mode forthe current depth block is determined in step 1320, where the currentIntra prediction mode belongs to a mode set comprising a Horizontal modeand a Vertical mode. A test “Mode=Horizontal?” is perform in step 1330.If the result is “Yes”, the process goes to step 1350. If the result is“No”, the process goes to step 1340. In step 1350, the predictionsamples are derived based on a reconstructed neighboring depth columnadjacent to a left block boundary of the current depth block bygenerating rows of the prediction samples from the reconstructedneighboring depth column. In step 1340, the process further tests“Mode=Vertical?”. If the result is “Yes”, the process goes to step 1360.If the result is “No”, the process goes to step 1370. In step 1360, theprediction samples are derived based on a reconstructed neighboringdepth row adjacent to a top block boundary of the current depth block bygenerating columns of the prediction samples from the reconstructedneighboring depth. In step 1370, the prediction samples are derived forother modes. After the prediction samples are derived, Simplified DepthCoding (SDC) is applied to the current depth block using the predictionsamples derived for the current depth block as shown in step 1380.

The flowchart shown above is intended to illustrate an example ofSimplified Depth Coding (SDC) with an extended Intra prediction modeset. A person skilled in the art may modify each step, re-arranges thesteps, split a step, or combine steps to practice the present inventionwithout departing from the spirit of the present invention.

The above description is presented to enable a person of ordinary skillin the art to practice the present invention as provided in the contextof a particular application and its requirement. Various modificationsto the described embodiments will be apparent to those with skill in theart, and the general principles defined herein may be applied to otherembodiments. Therefore, the present invention is not intended to belimited to the particular embodiments shown and described, but is to beaccorded the widest scope consistent with the principles and novelfeatures herein disclosed. In the above detailed description, variousspecific details are illustrated in order to provide a thoroughunderstanding of the present invention. Nevertheless, it will beunderstood by those skilled in the art that the present invention may bepracticed.

Embodiment of the present invention as described above may beimplemented in various hardware, software codes, or a combination ofboth. For example, an embodiment of the present invention can be acircuit integrated into a video compression chip or program codeintegrated into video compression software to perform the processingdescribed herein. An embodiment of the present invention may also beprogram code to be executed on a Digital Signal Processor (DSP) toperform the processing described herein. The invention may also involvea number of functions to be performed by a computer processor, a digitalsignal processor, a microprocessor, or field programmable gate array(FPGA). These processors can be configured to perform particular tasksaccording to the invention, by executing machine-readable software codeor firmware code that defines the particular methods embodied by theinvention. The software code or firmware code may be developed indifferent programming languages and different formats or styles. Thesoftware code may also be compiled for different target platforms.However, different code formats, styles and languages of software codesand other means of configuring code to perform the tasks in accordancewith the invention will not depart from the spirit and scope of theinvention.

The invention may be embodied in other specific forms without departingfrom its spirit or essential characteristics. The described examples areto be considered in all respects only as illustrative and notrestrictive. The scope of the invention is therefore, indicated by theappended claims rather than by the foregoing description. All changeswhich come within the meaning and range of equivalency of the claims areto be embraced within their scope.

1. A method of Intra coding for a block in a coding system, the methodcomprising: receiving input data associated with a current block;determining a current Intra prediction mode for the current block;deriving prediction samples for the current block based on reconstructedneighboring samples according to the current Intra prediction mode,wherein a predicting value representing a single prediction value forthe current block is determined based on at least two corner samplescorresponding to the current block according to the current Intraprediction mode; and applying encoding or decoding to the input dataassociated with the current block using the prediction samples derivedfor the current block.
 2. The method of claim 1, wherein the at leasttwo corner samples corresponding to the current block comprise twocorner prediction samples of a left-most column of the current block ifthe Horizontal mode is selected.
 3. The method of claim 1, wherein theat least two corner samples corresponding to the current block comprisetwo corner reconstructed samples of the reconstructed neighboring columnadjacent to a left block boundary of the current block if the Horizontalmode is selected.
 4. The method of claim 1, wherein the at least twocorner samples corresponding to the current block comprise two cornerprediction samples of a top row of the current block if the Verticalmode is selected.
 5. The method of claim 1, wherein the at least twocorner samples corresponding to the current block comprise two cornerreconstructed samples of the reconstructed neighboring row adjacent to atop block boundary of the current block if the Vertical mode isselected.
 6. The method of claim 1, wherein the at least two cornersamples corresponding to the current block comprise four cornerprediction samples of the current block.
 7. The method of claim 6,wherein predicting value is determined using a mean median, maximum,minimum, or linear combination of said four corner prediction samples ofthe current block.
 8. The method of claim 1, wherein the at least twocorner samples corresponding to the current block comprise two cornerprediction samples of a line of the current block adjacent to a blockboundary of the current block according to the current Intra predictionmode for the current block.
 9. The method of claim 1, wherein the atleast two corner samples corresponding to the current block comprise twocorner reconstructed samples of reconstructed neighboring line adjacentto a block boundary of the current block according to the current Intraprediction mode for the current block.
 10. An apparatus for Intra codingof a block in a coding system, the apparatus comprising one or moreelectronic circuits configured to: receive input data associated with acurrent block; determine a current Intra prediction mode for the currentblock; derive prediction samples for the current block based onreconstructed neighboring samples according to the current Intraprediction mode, wherein a predicting value representing a singleprediction value for the current block is determined based on at leasttwo corner samples corresponding to the current block according to thecurrent Intra prediction mode; and apply encoding or decoding to theinput data associated with the current block using the predictionsamples derived for the current block.